Global temperature records are expected to exceed the 1.5 °C threshold for the first time this year. This has happened much sooner than predicted. So can life on the planet adapt quickly enough?

In our new research, published today in Nature, we explored the ability of tiny marine organisms called plankton to adapt to global warming. Our conclusion: some plankton are less able to adapt now than they were in the past.

Plankton live in the top few metres of ocean. These algae (phytoplankton) and animals (zooplankton) are transported by ocean currents as they do not actively swim.

Climate change is increasing the frequency of heatwaves in the sea. But predicting the future effects of climate change is difficult because some projections depend on ocean physics and chemistry, while others consider the effects on ecosystems and their services.

Some data suggest that current climate change have already altered the marine plankton dramatically. Models project a shift of plankton towards both poles (where ocean temperatures are cooler), and losses to zooplankton in the tropics but might not predict the patterns we see in data. Satellite data for plankton biomass are still too short term to determine trends through time.

To overcome these problems, we have compared how plankton responded to past environmental change and modelled how they could respond to future climate changes. As the scientist Charles Lyell said, “the past is the key to the present”.

We explored one of the best fossil records from a group of marine plankton with hard shells called Foraminifera. This comprehensive database of current and past distributions, compiled by researchers at the University of Bremen, has been collected by hundreds of scientists from the seafloor across the globe since the 1960s. We compared data from the last ice age, around 21,000 years ago, and modern records to see what happened when the world has previously warmed.

We used computational models, which combine climate trends with traits of marine plankton and their effect on marine plankton, to simulate the oceanic ecosystems from the last ice age to the pre-industrial age. Comparing the model with the data from the fossil record is giving us support that the model simulated the rules determining plankton growth and distribution.

We found that some subtropical and tropical species’ optimum temperature for peak growth and reproduction could deal with seawater warming in the past, supported by both fossil data and model. Colder water species of plankton managed to drift to flourish under more favourable water temperatures.

Our analysis shows that Foraminifera could handle the natural climate change, even without the need to adapt via evolution. But could they deal with the current warming and future changes in ocean conditions, such as temperature?

Future of the food chain

We used this model to predict the future under four different degrees of warming from 1.5 to 4 °C. Unfortunately, this type of plankton’s ability to deal with climate change is much more limited than it was during past warming. Our study highlights the difference between faster human-induced and slower-paced geological warming for marine plankton. Current climate change is too rapid and is reducing food supply due to ocean stratification, both making plankton difficult to adapt to this time.

Phytoplankton produce around 50% of the world’s oxygen. So every second breath we take comes from marine algae, while the rest comes from plants on land. Some plankton eat other plankton. That in turn gets eaten by fish and then marine mammals, so energy transfers further up the food chain. As it photosynthesises, phytoplankton is also a natural carbon fixation machine, storing 45 times more carbon than the atmosphere.

Around the world, many people depend heavily on food from the ocean as their primary protein sources. When climate change threatens marine plankton, this has huge knock-on effects throughout the rest of the marine food web. Plankton-eating marine mammals like whales won’t have enough food to prey on and there’ll be fewer fish to eat for predators (and people). Reducing warming magnitude and slowing down the warming rate are necessary to protect ocean health.

(Author: Rui Ying, Postdoctoral Researcher, Marine Ecology, University of Bristol and Daniela Schmidt, Professor in Palaebiology, University of Bristol

Disclosure Statement: Rui Ying received funding from China Scholarship Council for this study.

Daniela Schmidt received funding from NERC. She is a member of NERC Science Committee and the council of the Palaeontological Association.)

This article is republished from The Conversation under a Creative Commons license. Read the original article.
 

Three views of the desiccated remains of an extinct marsupial mammal called the Tasmanian tiger, or the thylacine, from a collection at the Swedish Museum of Natural History in Stockholm are seen in this undated handout image. Researchers managed to recover genetic material called RNA from the remains, a scientific first for an extinct species.
| Photo Credit: Reuters

The Tasmanian tiger, a dog-sized striped carnivorous marsupial also called the thylacine, once roamed the Australian continent and adjacent islands, an apex predator that hunted kangaroos and other prey. Because of humans, the species is now extinct.

But that does not mean scientists have stopped learning about it. In a scientific first, researchers said on Tuesday they have recovered RNA – genetic material present in all living cells that has structural similarities to DNA – from the desiccated skin and muscle of a Tasmanian tiger stored since 1891 at a museum in Stockholm.

Scientists in recent years have extracted DNA from ancient animals and plants, some of it upwards of 2 million years old. But this study marked the first time that RNA – much less stable than DNA – has been recovered from an extinct species.

While not the focus of this research, the ability to extract, sequence and analyse old RNA could boost efforts by other scientists toward recreating extinct species. Recovering RNA from old viruses also could help decipher the cause of past pandemics.

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) – biomolecular cousins – are fundamental molecules in cell biology.

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DNA is a double-stranded molecule that contains an organism’s genetic code, carrying the genes that give rise to all living things. RNA is a single-stranded molecule that carries genetic information it receives from the DNA, putting this information into practice. RNA synthesises the panoply of proteins that an organism requires to live and works to regulate cell metabolism.

“RNA sequencing gives you a taste of the real biology and metabolism regulation that was happening in the cells and tissues of the Tasmanian tigers before they went extinct,” said geneticist and bioinformatician Emilio Mármol Sánchez of the Centre for Palaeogenetics and SciLifeLab in Sweden, lead author of the study published in the journal Genome Research.

“If we want to understand extinct species, we need to understand what gene complements they have and also what the genes were doing and which were active,” said geneticist and study co-author Marc Friedländer of Stockholm University and SciLifeLab.

There were questions about how long RNA could survive in the type of conditions – room temperature in a cupboard – that these remains had been stored. The remains at the Swedish Natural History Museum were in a state of semi-mummification, with skin, muscles and bones preserved but internal organs lost.

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“Most researchers have thought that RNA would only survive for a very short time – like days or weeks – at room temperature. This is likely true when samples are wet or moist, but apparently not the case when they are dried,” said evolutionary geneticist Love Dalén of the Centre for Palaeogenetics.

The Tasmanian tiger resembled a wolf, aside from the tiger-like stripes on its back. The arrival of people in Australia roughly 50,000 years ago ushered in massive population losses. The 18th century arrival of European colonisers spelled doom for the remaining populations concentrated on the island of Tasmania, with a bounty later put on them after they were declared a hazard to livestock. The last-known Tasmanian tiger succumbed in a Tasmanian zoo in 1936.

“The story of the thylacine’s demise is in a sense one of the most well-documented and proven human-driven extinction events. Sadly, Tasmanian tigers were declared as protected just two months before the last-known individual died in captivity, too late for saving them from extinction,” Mármol said.

Private “de-extinction” initiatives have been launched aimed at resurrecting certain extinct species such as the Tasmanian tiger, dodo or woolly mammoth.

“Although we remain skeptical about the possibility of actually recreating an extinct species using gene editing on living extant animal relatives – and the time-scale to get to a final point might be underestimated – we do advocate for more research on the biology of these extinct animals,” Mármol said.